Elevator control



E. F. BANFIELD.

ELEVATOR CONTROL. APPLICATION man Diem, i918.

1,886,223. A n Patented Aug. 2,' 1921.

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UNITED STATES EDWIN F. BANFIELD, F ATLANTIC HIGHLANDS, NEW JERSEY.

ELEVATOR CONTROL.

Specification of Letters Patent.

Patented Aug. 2, 1921.

Application filed December 11, 1918. Serial No. 266,216.

To @ZZ whom t may concern Be it known that EDWIN l". BANFXELD, a citizenof the `United States, residing at tlantic Highlands, in the county ofMonmouth and YState of New Jersey, have invented new and usefullniproveinentsin Elevator Controls, of which the following is aspecification.

This invention relates to improve-ments inY elevator controls.

@ne of the objects of this invention is to provide an improve-d safetycontrol for preventing," the. operation of the elevator car unless thecar door is closed.

Another object is to provide an electrical safety control whereby theopen condition of the car door prevents the operation of the elevator.

Another object to prevent the inadvertent starting of the ele 'atorduringI inspection, cleaning, adjusting, repairing, etc., while the cardoor is open.

further object is to provide for theautomatic adjustment of the safetymechanism.

Another object is to provide a. safety control which may be readilyapplied to existinaelevator equipment. n

`Other objects and advantages will appear from the specification andclaims.

@ne embodiment of the invention is illustrated in the accompanying`drawing, wherein- Figure 1 shows, diagramniatically, the in- 'entionassociated with electrical elevator vstern. and.

n Fig. 2 shows a modification of one of the eatures.

In its preferred embodiment the invention comprehends a flexible cableextending along the elevator shaft in a. position to be under thecontrol of the car door in any position of the car. rThis cable actuatesa safety switch which causes the operating moto-r to be disconnectedfrom the line, to stop the car whenever the door is opened while the caris in motion, or to prevent the starting; of the car, if it is at rest,until the door is closed. To guard against the inadvertent starting,r ofthe car, by the manipulation of any part of the ordinary controllersvsteni. during' inspection` cleaning, adjustment, repairs. etc., whilethe door is open, a. masten switch is provided for entirely removing'the power from the controller systeni uiitil the door is closed.Automatic adjusting` and compensating means are also provided to insurethat the correct relation exists between the cable and safety switch sothat the control is always able to function properly.

Fig. 1 will irst be described.

An elevator car 5 is adapted to be moved up and down in the elevatorshaft or hatchway by an electric motor 6. The up-anddown movement isregulated by an operators-controller 7, carried in the car, through a`pair of electromagnetic direction switches 8 and 9. The power foroperating the motor is supplied through a master switch 10 and iscontrolled by a series of accelerating switches 11, 12, 13 and 14. Aflexible cable 15 extends along the elevator shaft and is actuated` bythe car door to control the condition of a safety switch 16. Vhen thedoor is open the safety switch is also open. If the door is opened whilethe car is in motion the safety switch causes the immediateI opening ofthe direction Switch and the master switch and the car is stopped. Tfthe car is at rest t-he opening' of the door causes the safety switch toopen the master switch and the car cannot be started until the door isclosed.

The flexible cable 15 is secured to the top of the elevator shaft andextends between two pairs of rollers 17 and 18 carried in iixedpositions on the car. rThe cable also passes between a pair of rollers19 secured to the free end of a. gate-actuated lever 20.

The cable and lever assume the positions.

shown in full lines when the door is closed and the positions shown b ythe dotted lines when the door is opened.

At the bottom of the shaft cable 15 passes around a pulley 21 and thenover a pulley 22 to which is secured the contact drum of safety switch1G. A freely suspended weight 28 is fastened to the lower end of thecable to keep it taut and to compensate for stretchingf and contraction,as will be hereinafter explained.

The amount the pulley and drum can be rotated is limited by a pair offixed stops 24: and 25 which are adapted t-o be engaged by an arm 26carried by pulley 22. Safety switch 16 has a. pair of contacts 27 and 28adapted to interconnect, respectively, two pairs of contacts 29 and 30when the drum is in the position shown by the full lines and todisconnect them when the drum is in the position shown by the dottedlines.

The entire system can be fully understood there is no interruption inthe field connections across the line, provides dynamic bralring toprevent excessive coasting of the car. This shortcircuit is broken bythe energization of either switch 8 or switch 9 disconnecting therespective contacts 52 or There is, thus, no shortcircuiting of the lineat the time it is connected to the armature by one of the directionswitches.

lf, during the ascending of the car, the door should be opened, thelever 9.0 is moved to the dotted line position. This movement of lever2O flexes the cable, rotating pulley 22 and the drum of safety switch 16in the direction of the arrow and disconnecting contacts 29 and 30, asbefore. The disconnection of contacts SOvopens the circuit for thewinding of direction switch 8. Switch 8 returns to normal position,interrupting the line connections to the motor armature 'and providingthe dynamic brake shortcir cuit, through resistance 73, as previouslydescribed.

ln order that the motor may act as a generator to secure the properdynamic braking action, it is necessary to maintain the field excitationof the motor until the car is stopped. This is accomplished by retainingthe master switch closed in spite of the fact that the circuit for itswinding through contacts 529 has been opened by the rotation of the drumof the safety switch. The master switch has an auxiliary pair ofcontacts T6, which are closed when the master switch is closed and openwhen the master witch is open. Accelerator switch 1e also has a pair ofstationary contacts 77 adapted to be interconnected by a movable contact78 when the switch is energized. rThese two sets of contacts control aby-pass circuit for winding 37, including conductors 79 and SO, which isindependent of contacts 29. rlhus. when the master switch has once beenclosed, it is independent of safety switch 16 l`s long as acceleratorswitch 14 is energized. llhen, therefore, power is removed. from theperating motor by the opening of the door uri-ing the movement of thecar, the master Nwitch remains closed and dynamic braking action isprovided until the motor has so decreased its speed that acceleratorswitch 1e is denergized. The accelerating switches are usuallydenergized at aconsiderably lower currentvalue than that at which theyoperated so that the desired braking action can be readily obtained.rThe auxiliary switch need not be placed on the last accelerator switchbut may be associated with any of the accelerating switches.

T he master switch can be readily arranged to be placed in a cabinetwhich can be made inaccessible to the ordinary cleaner and repairman. Byhaving the by-pass circuit include contacts 76, it is thus impossiblefor the inadvertent manual manipulation of the In order to prevent themotor from being thrown upon the line without all the startingresistance in circuit, as might be the case if the operator could, byquickly reversing the position of arm 39 of his' controller, connect themotor armature in circ-uit in a reverse direction before theaccelerating switches are denergized, the energizing circuits of thewindings of direction switches 8 and 9 pass through contacts t9 onaccelerating switch 11. These contacts are shunted by a resistance 81,which is sufficiently high to prevent the operation of trie switches 8or 9 when it is in series with their operating windings. Theshortcircuiting of this resistance by the de'c'nergizing of acceleratingswitch 11 allows suilicient current to flow, when controller arm 39 ismade to engage contacts c or T2, to effect the operation of directionswitch 8 or 9. Thus the operator cannot connect the motor to the linewithout all of the starting resistance being in circuit.

Fig. 2 shows a. modiiied arrangement for controlling the master switchby-pass circuit, to insure dynamic braking when the door is opened whilethe car is in motion. instead of having the by-pass circuit controlledby contacts on one of the accelerating switches, a counter voltage relay82 may be connected across the motor armature. )i pair of lined contacts83 and 84 of relay 82 are connected, respectively, to the positive lineand the righthand auxiliary contact 76, These contacts then bear thesame relation to the by-pass circuit as do contacts 7l' when theaccelerating switch is used for the control. Then the counter voltagerelay 82 is suiiiciently energized by the counter-electromotive force ofthe inotor, its armature interconnects contacts 83 and Se, closing theby-pass circuit of the master switch with the same result as previouslydescribed. The counter voltage relay arrangement is particularly adaptedfor equipments where the safety control is added to existinginstallations. No change need be made in the accelerating switchesalready in place. lt is also particularly adapted for elevatorequipments which depend upon other means than counter voltageaccelerating switches for controlling the motor current.

The stretching and contraction of cable 15 is automatically compensatedfor by having the cable pass over the pulley 22 of safety switch 16 andheld taut by a freely suspend ed weight. The drum in being moved to itsnormal position by the pull of the weight is always stopped in adefinite position by arm 26 engaging stop 25. The weight, exerating aconstant pull. on the cable, thus maintains a constant tension on thecable, which"v slips on pulley 22 just enough to be kept taut. Thelengthening or shortening of thc cable, therefore, has no injuriouseffect upon the operation of the safety switch.

The violent or repeated opening of the door might, because of themomentum of the drum switch, cause the cable to slip over pulley 22 farenough in the reverse direction to prevent the subsequentinterconnection of contacts 29 and contacts 80 when the door is closed.This would prevent the operation of the elevator even though the doorwas shut. Such a con'ditionis obviated by providing the stop 24 in sucha. position that it is engaged by arm 26 upon a small movement of thedrum caused by a slight opening of the door. During the remainder of theflexing of the cable caused by the completion of the opening of the doorthe cable slips on pulley 22. Whenever the door is closed there is,therefore, enough movement of the cable to insure that arm 26 willengage stop 25, in which position contacts 29 and contacts 30 areinterconnected and the elevator may be started. By' the proper spacingof stops 2e and 25 the correct positioning of the interconnectingcontact-s 27 and 28 is insured for both the. open and closed conditionsof the door. 1t has been found that satisfactory results can be obtainedby having the stops comparatively close together and arranging thecontacts so that interconnection and disconnection are accomplished by aslight rotation of pulley 22. The desired friction of cable 15 uponpulley 22, to insure proper operation of the drum safetyswitch and notto render the movement of the door difficult, can be obtained by makingthe pulley 21 adjustable in an upward and downward direction so that theamount of the circumference of pulley" 22 engaged by the cable can beincreased or decreased.

1n case cable 15 should break while the door is closed, a counter-weightmoves the drum of safety switch 16 in the direction of the arrow,breaking the connections between contacts 29 and contacts 30. Masterswitch 10 is, thereupon denergized and the car cannot be operated untilthe cable is repaired. if the cable breaks while the car isrunning, itis immediately stopped. 1n case the break occurs while the door is open,and consequently the connections between contacts 29 and 30 are alreadybroken, counter-weight 85 holds the drum of safety switch 16 in thatposition. The master switch cannot be closed and the elevator cannotbestarted. @ther means than a counterweight may be used to rotate the drumof safety switch 16 when the cable breaks. For example, a spring actingin opposition to weight 23 may be employed. y, Y

While the invention has been described in connection with one type ofelectrical elevator equipment, it will be readily understood that it maybe employed with other types and that its use is not confined toelectrically operated elevators.

The shaft and car doors may be suitably interloclred, so that both mustbe closed before the elevator can be operated. One form of interlock isdisclosed in my Patent No. 1,293,688, granted Feb. 11, 1919.

The invention claimed is:

1. rin elevator control having a source of power for raising andlowering the elevator car, an electromagnetic's'witch for controllingsaid source in raising' the car, an electromagnetic switch for'controlling said source in lowering the car, means actuated by the caroperator for controlling both said electromagnetic switches, a safetyswitch for causing' the operation of either electromagnetic switch toprevent further movement of the" car independentlyV of said means, and

a member extending along the elevator shaft and operable by the movementof the car door in any position of the car to control said safetyswitch.

2. in elevator control comprising a masswitch for controlling theapplication of power' to the elevator car, a safety switch forcontrolling said master switch, and a cable extendingalong the elevatorshaft and operated by the car door for controlling said safety switch,whereby the application of power to the elevator is under the controlofthe door thereof( Y il. in elevator control comprising anelectromagnetic master switch for controlling the application of powerto the elevator motor, safety mechanism under the influence of theelevator door for controlling said master switch, and means dependentupon theV operating conditions of the elevator motor for modifying theycontrol of said safety mechaiism over said master switch.

a. Aln elevator control comprising an electromagnetic master switch forcontrolling the application of power to the elevator, accelerationcontrol means for governing the speed of the elevator, safety mechanismunder the influence of the elevator door for controlling said masterswitch, and means associated with said acceleration control means formodifying the control of said safety mechanism over said master switch.

An elevator control having mechanism for raising and lowering theelevator car, a 1able extending along the elevator shaft and actuated bythe car door for controlling said mechanism, and means for automaticallycompensating for stretching or contraction of said cable'.

.6. An elevator control having mechanism for operating the elevator car,a cable extending along the elevator shaft and actuated by the car doorfor controlling said mechanism, and means for automatically maintainingthe operative relation between said cable and said mechanism.

'7. A control for elevator operating means comprising a cable extendingalong the elevator shaft and under the control of the car door, safetymechanism controlled by said cable for preventing the operating meansfrom moving the car when the door thereof is open, and means for causingsaid safety mechanism to prevent movement of the elevator if the cablebreaks.

8. An elevator control having mechanism for raising and lowering theelevator car, a fiexible cable fixed at one end and extending along theelevator shaft and controlled by the open and closed condition of thecar door, a safety switch including a rotatable member for controllingsaid mechanism, said rotatable member being controlled by said cable,and a weight connected with the free end of the cable for automaticallycompensating for stretching or contraction of said cable.

9. An elevator control having mechanism for raising and lowering theelevator car, a iiexible cable extending along the elevator shaft andcontrolled by the open and closed condition of the car door, a safetyswitch, including a rotatable member, for controlling said mechanism,said rotatable member being controlled by said cable, means for limitingthe movement of the rotatable member in either direction, and meansassociated with the cable and coperating with said limiting means forautomatically maintaining the operative relation between the cable andsaid safety switch.

10. An elevator control having mechanism for raising and lowering theelevator car, a fiexible cable extending along the elevator shaft andactuated by the car door, a safety switch controlled by said cable andcontrolling said mechanism, said safety switch including a rotatableContact carrying drum engaged by said cable.

ll. A control for elevator operating means comprising a cable extendingalong the car shaft and under the control of the car door, safetymechanism including a switch mounted on a drum and controlled by saidcable for causing the operating means to stop the car when the car dooris opened, and a weight cooperating with the drum to cause the switch toopen if the cable breaks.

l2. A control for elevator operating moans comprising a cable extendingalong the car shaft and under the control of the car door, a switchcontrolled by said cable to cause the operating means to stop the car atany point of the shaft if the door is opened, said switch comprising adrum, contacts thereon, stops to limit the movement of the drum in eachdirection, and means for varying the arc of contact of the cable withthe drum to permit the cable to freely slide over said drum afterengaging a stop.

In witness whereof I have hereunto subscribed my name.

EDWIN F. BANFIELD.

